Semiconductor device fabrication often involves deposition of a stack of layers on an underlying wafer substrate. Typically, most deposition and other processing to form the devices occur on the front face of a wafer. As the deposited layers build up, they can introduce stress in the wafer. This stress can cause the wafer to bow, which is undesirable. Where bowing is significant, it can deleteriously affect subsequent processing steps.
Another issue that arises during semiconductor device fabrication is the production of particles on the back side of a wafer during post-deposition processing. These particles can cause local stress effects in the wafer, which are especially problematic during photolithography operations.
Thus, improved methods and apparatus for overcoming issues related to wafer stress and the presence of particles on the back side of a wafer are desired.